1. Field of the Invention
The present invention relates to a rack extension jig device which is used to add a rack or racks when aligning a plurality of racks straight along a lengthwise direction of the racks, and particularly concerns to a rack extension jig device improved so that the rack or racks are added quickly with a single operation.
2. Description of Related Art
A rack combined with a pinion has been known as a rack-and-pinion type steering device or a rack-and-gear device as disclosed by Japanese Laid-open Patent Application Nos. 08-34354, and 2000-65176 (each referred to as first and second reference hereinafter).
The first reference teaches that a helical spring is used as an urging means to absorb a displacement of the rack through a rotational movement of a rack guide means when a distance between the rack and the pinion fluctuates so as to reduce a frictional quantity of the rack guide means during the operation.
The second reference teaches that an elastic member is provided at a position lower than an addendum flank of the gear is placed. When the device is actuated, the gear is brought into engagement with the rack through an urging force of an intermediary elastic member so as to mitigate an induced level of noise and vibration.
Japanese Laid-open Patent Application No. 10-184842 (referred to as third reference hereinafter) teaches that racks are applied to a pinion device which requires a lengthened stroke upon transferring a factory robot, a component part stocker or a washing line.
In this instance, a new rack or racks are add when aligning a plurality of racks straight along a lengthwise direction of the racks as shown in FIG. 14.
In FIG. 14, a rack extension jig tool 50 has a hand grip body 50A, a lateral side of which has a plurality of pins 51a-51d directed along a tooth ridge Q of racks 52, 53. As shown in FIG. 15, the pins 51a-51d are handled to bring the pins 51a-51d into engagement with the respective rack teeth 51e-51h, so as to align the racks 52, 53 straight at the predetermined pitch interval Tp therebetween.
Since the pins 51a-51d are supported by the hand grip body 50A in a canti-lever fashion, it is necessary to use the hand grip body 50A to strongly engage the pins 51a-51d with the respective rack teeth 51e-51h when adding the rack to align straight.
Namely, the rack extension jig tool 50 requires a user to rotationally urge the pins 51a-51d toward the respective rack teeth 51e-51h with an assist of a rotational moment W. This makes the user cumbersome to operate the hand grip body 50A, which hinders the rack extension jig tool 50 to be user-friendly. The cumbersome operation renders the rack extension jig tool 50 difficult to readily and smoothly engage the pins 51a-51d with the respective rack teeth 51e-51h with a single operation.
Therefore, the present invention has been made with the above drawbacks in mind, it is a main object of the invention to provide a rack extension jig device which is capable of readily and positively engaging tooth projections with the respective rack teeth to make a rack-adding operation quick and user-friendly with a single operation when adding a rack or racks to an array of other racks.